It is believed that feed additives which improve gut health and provide a more balanced gut microflora will promote growth of an animal.
In recent years, passive immunotherapy by oral administration of specific antibodies against gastrointestinal pathogens has been studied extensively in animals. Furthermore, there has been increasing interest in developing avian polyclonal antibodies for treatment of gastrointestinal diseases caused by various pathogens. As orally administered antibodies would provide the advantage of reduced cost and ease of administration for the treatment of enteric diseases, as an alternative to antibiotics. The aim of efficient pork production is to maximize lean meat yield while minimizing production cost. It has been established that two important factors contributing to lean growth are improving health status and the prevention of specific diseases. Enterotoxigenic E. coli (ETEC) strains that express K-88 fimbriae are a major cause of diarrhea and death in neonatal and newly weaned pigs resulting in major economic loss to the pork industry. It has been estimated that K-88-mediated ETEC are responsible for 50% of the 10 million baby pig deaths each year. Historically, antibiotics and animal plasma proteins have helped to reduce the detrimental effects of this condition. However, there is mounting pressure to discontinue the use of antibiotics and animal plasma proteins in swine industry, due to the concerns of human health. Many antibiotics and plasma proteins are banned for use in swine diets in Europe and will most likely be restricted in North America. Therefore, researchers have taken keen interest in searching for alternative therapies to antibiotics that could be used in swine nutrition, particularly during the nursery phases. Passive immunotherapy has been shown to have prophylactic and therapeutic benefits for controlling disease and improving livestock growth performance. Avian (egg) antibodies developed against ETEC can be transferred to the recipient by oral administration through supplementation of the normal diet of post-weaning piglets, thereby preventing the ETEC disease in piglets and acting as an effective growth promoter. Orally administered antibodies provide the advantage of reduced cost and ease of administration for the treatment of enteric disease as well as for improvement of gut health, the key requirement for the improved growth performance, offering effective and sustainable replacements for both plasma proteins and antibiotics